Hydraulic press



April 26, 1966 c. HAMMON HYDRAULIC PRESS 2 Sheeos-Sheet '1 Filed May 21, 1964 FIG.I

l CARL HAMMON BY A an-i126, 1966 c. HAMMON 3,

HYDRAULIC PRESS Filed May 21, 1964 2 Sheets-Sheet 2 INVENTOR.

CA RL HAMM ON 25 K/MI/M FIG. 3

United States Pat ent 3,247,783 1 HYDRAULIC PRESS Carl Hammon, Erie, Pa., assignor to Erie Foundry Company, Erie, Pa., a corporation of Pennsylvania Filed May 21, 1964, Scr. No. 369,135 1 Claim. (Cl. 100-214) This invention relates to presses and, more particularly, to the type of press ordinarily used for cold forging and the like.

The press disclosed is a simple beam type design tied together with pre-stressed tie rods and spaced with keyed in spacers loaded at each end with a balanced hydraulic force supplied by the fluid supply from the main cylinder which is connected to the fluid supply line of the balance cylinder. This design permits a tie rod to stretch and top and bottom beams to deflect, yet at the same time it holds the working surface between the platen and wear plate parallel under maximum load.

The foregoing is achieved with a small balance cylinder and a spacer or long cylinder located at the back of the press. The balancing cylinder located at the back of the press and the main cylinder located in front of the press are connected in series to a hydraulic source so that the hydraulic pressure will be the same in both cylinders at all times. The ratio of the effective piston area of the balancing cylinder to the effective piston area of the main cylinder is suchas to generate a moment equal to .the moment generated by the main cylinder about the center line of the tie rod.

This design eliminates multiple accumulated deflections due to tension, compression, and stretch multiplied by a distance from the neutral axis of the press frame and fatigue stresses which are present in ordinary types of be used in presses for injection molding, die casting, and

extrusion work and other similar applications where it is desirable to keep two relatively moving surfaces in parallel relation with each other.

It is accordingly, an object of the invention to provide a press having a compensating means for maintaining the platens of a press in parallel relation with each other.

Another object is to provide an improved press.

Still another object of the invention is to provide a press which is simple in construction and minimum in size and weight for a particular purpose.

With the above and other objects in view, the present invention consists of the combination and arrangement of parts hereinafter more fully described, illustrated in the accompanying drawing and more particularly pointed out in the appended claims, it being understood that changes may be made in the form, size, proportions, and minor details of construction without departing from the spirit or sacrificing any of the advantages of the invention.

In the drawings:

FIG. 1 is an isometric view of a press according to the invention;

FIG. 2 is a cross sectional view taken on line 2-2 of FIG. 1; and

FIG. 3 is a view taken on line 3-3 of FIG. 1.

Now with more particular reference to the drawings, the press is basically made up of a bottom beam 11 and a top beam 12 supported in spaced relation from each other by means of a tie rod 13 and spacer 14. A main 3,247,783 Patented Apr. 26, 1966 mice cylinder 15 is supported above a platen 16 and a balance cylinder 17 is supported between the rearwardly extending portions of the top beam and bottom beam. Thus the top beam 12 acts as a second class lever with its fulcrum at tie rod 13. The balance cylinder is hydraulically connected to the main cylinder 15. Balance cylinder 15 is supported on the front of top beam 12. The press may be so designed that the product of the effective area of the main cylinder times the lever arm measured from the center of the tie rod 13 to the axial center of the main cylinder 15 is equal to the effective area of the balancing cylinder 17 times the distance from the axial center line of the balance cylinder to the axial center of the tie rod 13. Thus, the design eliminates multiple accumulated deflections due to tension, compression, and strain multiplied by a distance from the neutral axis of the press. It also eliminates fatigue stresses which are present in other types of C-frame press designs. The top beam 12 may be fabricated from steel according to good design practice and it has an opening 23 therethrough which receives the upper end of the tie rod 13. The lower side of the upper beam is supported on the spacer 14. The spacer 14 may be of any suitable column construction, either tubular or other suitable shape, and there may be one or more spacers and one or more tie rods. The bottom beam 11 may have the lower end of the spacer 14 resting on it and the tie rod 13 may extend through the opening 24 in the lower beam and have a nut 25 on the lower end thereof. The upper end of the tie rod may have a nut 26 on it. Thus, the tie rod 13 may be prestressed.

The main cylinder 15 is attached to the front end of top beam 12in a suitable manner in accordance with good design practice and its piston rod 27 fixed to piston 48 may be attached to the wear plate structure 19 which may be in the form of an upper platen. The wear plate may be supported on a guiding mechanism which may be guided up and down on the fixed structure at 27'.

The bottom beam 11 may be fabricated in accordance with good design practice and has the platen 16 supported on the front portion thereof.

The balance cylinder 17 may be fixed to the plate 47 which is, in turn, fixed to spacer 37 which is, in turn, fixed to the rear end of the top beam at 28 and its piston rod may be connected to'the rear end of the bottom beam at 29. A hydraulic line 30 from a suitable hydraulic pump which may be a part of the machine is connected to the main cylinder 15 at 31 and to the balance cylinder 17 at 32. The plate 47 is returned by hydraulic fluid from valve 51 and line 50. The four-way valve 51 controls the fluid. The distance L1 from the axial center line 33 of the tie rod to the axial center line 34 of the main cylinder 15 is of a predetermined value relative to the distance L2 from the center line 33 to the center line 35 of the balance cylinder 17. The press will be so designed that the product of L2 times the effective area A1 of the balance cylinder 17 is equal to the product of L1 times the effective area A2 of the piston of main cylinder 15. Thus, the moment of 11.2 times A2 (the effective area of the balance cylinder) will be equal to the moment L1 times Al (the effective area of the main cylinder 15). In this manner, the tendency of the bottom beam to bend on the platen side is compensated for by the balance cylinder. The tendency of the platen to separate from the wear plate 19 is also minimized.

The balance cylinder is held down by springs 40 which are held in place on bolts 41 by nuts 42. A balance spacer 37 is provided. The upper end of the spacer 37 is fixed to the top beam 12 and the lower end of the spacer 37 is fixed to plate 47 which is, in turn, fixed to cylinder 17. The bolts 41 pass through plate 47. When the balance piston 49 in cylinder 17 extends, springs 40 are compressed. Then, springs 40 expand and urge the piston 17 to its neutral. position when the fluid pressure is relieved from line 50.

In the machine which is shown by example, the bottom beam 11 can be considered to be the base indicated at 20, the bottom beam having the working surface there- The foregoing specification sets forth the invention in its preferred practical forms but the structure shown is capable of modification within a range of equivalents without departing from the invention which is to be understood is broadly novel as is commensurate with the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

A press comprising a bottom beam,

a top beam supported in spaced relation to said bottom beam,

a tubular spacer having a lower end and an upper end,

a platen on said bottom beam,

said tubular spacer having its lower end supported on said bottom beam and its upper end supporting said top beam at an intermediate part of said top beam,

a main cylinder attached to said top beam spaced from said spacer and above said bottom beam,

said main cylinder having a main piston therein,

an upper platen,

means attaching said main piston to said upper platen,

a tie rod extending through said tubular spacer,

said tie rod having a first end and a second end,

said first end terminating above said top beam,

said second end terminating below said bottom beam,

first nut means on said first end of said tie rod overlying and engaging said top beam,

second nut means on said second end of said tie rod,

said second nut means engaging and underlying said bottom beam,

a balance cylinder having a balance piston and a piston rod therein,

an elongated balance spacer attached to said balance cylinder at its lower end,

said balance piston rod engaging said bottom beam at a position spaced from said tubular spacer and on the side thereof remote from said upper platen,

said balance spacer begin fixed to said top beam at a position thereon spaced from said tubular spacer,

fluid pressure means,

said fluid pressure means being connected to said balance cylinder above said balance piston,

said fluid pressure means being connected to said main cylinder above said main piston,

said main cylinder and said balance cylinder being connected in parallel with each other,

said main cylinder and said balance cylinder each having an effective area,

said main piston being disposed from said tie rod a first distance and said balance piston being disposed from said tie rod a second distance,

the ratio of said main cylinder effective area to said first distance being equal to the ratio of said balance cylinder area to said second distance,

said tie rod being disposed between said main cylinder and said balance cylinder,

fluid pressure means connected to said main cylinder below said main piston to return said main piston to a neutral position,

and spring means connected to said spacer and means connecting said spacer to said bottom beam to return said balance cylinder to a neutral position.

References Cited by the Examiner UNITED STATES PATENTS 2,296,051 9/1942 Pocock et a1 l00231 2,580,078 12/1951 Denison -231 2,869,177 1/1959 Jurgeleit l002l4 X 3,030,879 4/1962 Lasko l002l4 X WALTER A. SCHEEL, Primary Examiner. 

